hey there, nice work, the digital ear I feel looks good. I think the difficulty stems more in how you approach the edges. Sharp vs smooth edges. I think the picture you use as reference for that digital ear is very good to study the form. Note for example the roots of the antehelix, one is in light and then there's a sharp edge as we see shadow beneath.
The way you rendered it, it looks thicker than it actually is as you gave it a lighter shadow under a highlight. Also, the highlight on the body of the antehelix is sharply demarcated among two shadow areas and another sharply demarcated, thin dark shadow which makes the rendering seem a bit uneven there and at the same time makes the helix look inflated and making a tight notch with the antehelix
As for the apple, I think you are better served with a different light angle to practice the shading, especially in graphite as the very dark shadows are hard to render in graphite - I feel even a 10B pencil struggles - maybe combining with charcoal or a charcoal oil pencil
cheers